Physico-chemical Aspects of Sex in Plants.

Abstract

The excellent review by Joyet-Lavergne of the earlier work on this problem obviates the need of recapitulation here. It may be stated, however, that the formative responses of the sexes in dioecious plants under various conditions have been much more thoroughly recorded than their concomitant physiology. This investigation was undertaken in an attempt to secure comprehensive data concerning normal staminate and pistillate metabolism in typical dioecious plants. For comparison of long and short day photoperiodic responses, data are presented for spinach and hemp as representative of these two types. Plants were grown in the greenhouse in the early spring and summer in triplicate series which were thinned to between 50 and 100 plants each, depending upon the age at which they were to be analyzed. The vegetative-reproductive cycle was controlled by supplementing daylight with electric light as needed at the rate of two 100-watt lamps per square yard at the height of one foot above plants. It was necessary to lengthen the early spring daylight 6 to 7 hours per day to prevent young hemp from flowering prematurely. Otherwise all plants developed normally. Six to 10 plants of each series were analyzed in early flowering stages prior to shedding of pollen, and a similar number during incipient fruiting. Entire plants were gathered and divided into duplicate samples of whole tops and roots for analysis, the average of analyses of all series being reported. Each table thus represents data from a study of over 100 plants. Roots were washed free of soil, rinsed in distilled water and then dried for 30 minutes at room temperature.